Beschrijving:Flight 191 left the gate at Chicago-O'Hare at 14:59 and taxied to runway 32R. At 15:02 the flight was cleared for takeoff. The takeoff roll was normal until just before rotation at which time sections of the No. 1 engine pylon structure came off the aircraft. During rotation the entire no. 1 engine and pylon separated from the aircraft, went over the top of the wing, and fell to the runway. Flight 191 lifted off about 6,000 feet down the runway, climbed out in a wings level attitude, and reached an altitude of about 300 feet agl with its wings still level. Shortly thereafter, the aircraft began to turn and roll to the left, the nose pitched down, and the aircraft began to descend. As it descended, it continued to roll left until the wings were past the vertical position. The DC-10 crashed in an open field and trailer park about 4,680 feet northwest of the departure end of runway 32R. The aircraft was demolished during the impact, explosion, and ground fire. Two persons on the ground were killed.

PROBABLE CAUSE: "The asymmetrical stall and the ensuing roll of the aircraft because of the uncommanded retraction of the left wing outboard leading edge slats and the loss of stall warning and slat disagreement indication systems resulting from maintenance-induced damage leading to the separation of the no.1 engine and pylon assembly procedures which led to failure of the pylon structure.Contributing to the cause of the accident were the vulnerability of the design of the pylon attach points to maintenance damage; the vulnerability of the design of the leading edge slat system to the damage which produced asymmetry; deficiencies in FAA surveillance and reporting systems which failed to detect and prevent the use of improper maintenance procedures; deficiencies in the practices and communications among the operators, the manufacturer, and the FAA which failed to determine and disseminate the particulars regarding previous maintenance damage incidents; and the intolerance of prescribed operational procedures to this unique emergency."

On June 6, 1979, after a series of postaccident inspections disclosed damaged aft bulkheads in the wing to engine pylons, the Administrator of the FAAissued an Emergency Order of Suspension. The Order suspended the DC-10 series aircraft type certificate "until such time as it can be ascertained that the DC-10 aircraft meets the certification criteria of Part 25 of the FAR and is eligible for a Type Certificate."On June 26, 1979, the FAA issued Special Federal Aviation Regulation 40 which prohibited the "operation of any Model DC-10 aircraft within the airspace of the United States." On July 13, 1979, after a series of formal investigations, the Administrator found that the DC-10 met the requirements for issuance of a type certificate. Accordingly, the Emergency Order of Suspension was terminated.

In November 1979 the FAA fined American Airlines $500,000 for using a faulty maintenance procedure on its DC-10 aircraft by using forklift trucks to mate the complete engine/pylon assembly with wing attachment points. Continental Airlines was fined $100,000 on a similar charge.

ISSUE A TELEGRAPHIC AIRWORTHINESS DIRECTIVE TO REQUIRE AN IMMEDIATE INSPECTION OF ALL DC-10 AIRCRAFT IN WHICH AN ENGINE PYLON ASSEMBLY HAS BEEN REMOVED AND REINSTALLED FOR DAMAGE TO THE WING-MOUNTED PYLON AFT BULKHEAD, INCLUDING ITS FORWARD FLANGE AND THE ATTACHING SPAR WEB AND FASTERNERS. REQUIRE REMOVAL OF ANY SEALANT WHICH MAY HIDE A CRACK IN THE FLANGE AREA AND EMPLOY EDDY-CURRENT OR OTHER APPROVED TECHNIQUES TO ENSURE DETECTION OF SUCH DAMAGE. (Closed - Acceptable Action)

Issued: 04-JUN-1979

To:

A-79-046

ISSUE A MAINTENANCE ALERT BULLETIN DIRECTING FAA MAINTENANCE INSPECTORS TO CONTACT THEIR ASSIGNED CARRIERS AND ADVISE THEM TO IMMEDIATELY DISCONTINUE THE PRATICE OF LOWERING AND RAISING THE PYLON WITH THE ENGINE STILL ATTACHED. CARRIERS SHOULD ADHERE TO THE PROCEDURE RECOMMENDED BY THE DOUGLAS AIRCRAFT COMPANY SERVICE BULLETIN WHICH INCLUDE REMOVING THE ENGINE FROM THE PYLON BEFORE REMOVING THE PYLON FROM THE WING. (Closed - Acceptable Action)

Issued: 22-JUN-1979

To:

A-79-052

ISSUE A MAINTENANCE ALERT BULLETIN TO U.S. CERTIFICATED AIR CARRIERS, AND NOTIFY STATES THAT HAVE REGULATORY RESPONSIBILITIES OVER FOREIGN AIR CARRIERS OPERATING DC-10 AIRCRAFT, TO REQUIRE APPROPRIATE STRUCTURAL INSPECTIONS OF THE ENGINE PYLONS FOLLOWING ENGINE FAILURES INVOLVING SIGNIFICANT IMBALANCE CONDITIONS OR SEVERE SIDE LOADS. (Closed - Acceptable Alternate Action)

INSURE THAT THE DESIGN OF TRANSPORT CATEGORY AIRCRAFT PROVIDES POSITIVE PROTECTION AGAINST ASYMMETRY OF LIFT DEVICES DURING CRITICAL PHASES OF FLIGHT; OR, IF CERTIFICATION IS BASED UPON DEMONSTRATED CONTROLLABILITY OF THE AIRCRAFT UNDER CONDITION OF ASYMMETRY, INSURE THAT ASYMMETRIC WARNING SYSTEMS, STALL WARNING SYSTEMS, OR OTHER CRITICAL SYSTEMS NEEDED TO PROVIDE THE PILOT WITH INFORMATION ESSENTIAL TO SAFE FLIGHT ARE COMPLETELY REDUNDANT. (Closed - Unacceptable Action)

Issued: 21-DEC-1979

To: FAA

A-79-100

INITIATE AND CONTINUE STRICT AND COMPREHENSIVE SURVEILLANCE EFFORTS IN THE FOLLOWING AREAS (Closed - Unacceptable Action)

Issued: 21-DEC-1979

To: FAA

A-79-101

ASSURE THAT THE MAINTENANCE REVIEW BOARD FULLY CONSIDERS THE FOLLOWING ELEMENTS WHEN IT APPROVES AN AIRLINE/MANUFACTURER MAINTENANCE PROGRAM (Closed - Unacceptable Action)

REVISE 14 CFR 121.707 TO MORE CLEARLY DEFINE "MAJOR" AND "MINOR" REPAIR CATEGORIES TO INSURE THAT THE REPORTING REQUIREMENT WILL INCLUDE ANY REPAIR OF DAMAGE TO A COMPONENT IDENTIFIED AS "STRUCTURALLY SIGNIFICANT." (Closed - Unacceptable Action)

Issued: 21-DEC-1979

To: FAA

A-79-104

EXPAND THE SCOPE OF SURVEILLANCE OF AIR CARRIER MAINTENANCE BY (Closed - Unacceptable Action)